Cultures of 638 routine preoperative conjunctival specimens prior to retinal detachment surgery demonstrated bacterial contamination with Staphylococcus epidermidis in 37%, S aureus in 3%, Proteus in 1%, Klebsiella in 1%, and Pseudomonas in 0.2%. Postoperative infection with rejection of the scleral implants occurred in 4% (37) of 878 operations. The risk of a clinical infection was increased statistically when a preoperative culture demonstrated pathogenic bacteria, when episcleral solid silicone was used in surgery, and when the procedure was a reoperation. Age, sex, side of surgery, type of anesthesia, aphakia, preoperative contamination with S epidermidis, drainage of subretinal fluid, disinsertion of muscles, or the use of silicone sponges did not influence the vulnerability of the eyes to postoperative infections. The risk of recurrent detachment following surgical removal of the infected materials was found to be 33%.